1. Field of the Invention
The present invention relates to a method of forming a pattern and a solid-state image sensor device.
2. Description of the Related Art
A CMOS image sensor (a CMOS solid-state image sensor device) is configured by forming a unit pixel by a photodiode that functions as a light receiving unit and a plurality of pixel transistors, and two-dimensionally arranging a plurality of the unit pixels (see Patent Documents 1 and 2, for example). It is important to suppress color mixture caused by a leakage of a photo-electrically converted electric charge to adjacent pixels in the CMOS image sensor. Thus, a method has been suggested in which an element isolation region that physically isolates the unit pixels is formed in a silicon layer of a substrate to suppress the leakage of the electric charge to the adjacent pixels.
However, when forming the element isolation region by etching, there may be a case where an interface state is generated, due to a residual product at an etching interface, to cause a generation of a white point. Further, there is a possibility that an electrical noise is generated in a device due to a fluorine (F) component in the residual product deposited at the etching interface. Thus, it is necessary to remove the residual component, particularly the fluorine residual component, deposited at the etching interface after the etching step.
Here, a cleaning method using wet etching may be considered to remove the fluorine residual component. However, if wet etching is performed after the etching step, for a structure in which a substrate, on which the unit pixels are formed, and a support substrate are bonded, there may be a case where an adhesive agent bonding the substrate and the support substrate dissolves.
Further, a cleaning method may be considered in which the fluorine residual component deposited at the etching interface is vaporized by heat treatment. However, for the above described bonded structure, there may be a concern that the unit pixels formed on the substrate are damaged by the heat treatment.